If you have selected wrong Finished Grade code and released it after assigning batch number, it can still be corrected if no components have been issued.

• Go to Manufacturing > Execution > Released Prod. Orders
• Select the production order and open in Edit mode
• Select correct item code in Source No. field
• Click on Refresh Production Order button on ribbon.

But, this activity shall be done before issuance otherwise it may create inconsistency in inventory.